In heavy duty mining or construction machinery, a number of different types of brake cooling systems for brakes in a vehicle axle assembly are often utilized. Some systems use the engine or power unit of the vehicle for brake cooling whereas others may use air to oil coolers or circulate a cooler fluid through the oil at the axle assembly itself.
Another need for brake cooling systems is found in trailers designed to haul heavy duty mining equipment such as shovels and mine haulage trailers, e.g., bottom dump trailers, and the like. FIG. 1 shows a typical lowboy trailer 90 having a trailer bed 91 for supporting heavy machinery 92, a gooseneck 93, a hauling vehicle 95, trailer wheels 97 (one shown), and a trailer axle assembly represented by numeral 99. The assembly 99 includes an axle with brakes (both not shown) for trailer operation, wherein the brakes are controlled by the operator in the hauling vehicle 95 that attaches to the trailer via the gooseneck 93. See also U.S. Pat. No. 6,113,338 to Smith (incorporated in its entirety herein).
One problem that has arisen for cooling trailer brakes is caused by the increase use of a removable gooseneck hitch for the trailers, as disclosed in U.S. Pat. No. 5,435,586 to Smith, also incorporated in its entirety by reference, and depicted in FIG. 1. These types of hitches permit the trailer size to increase, thus allowing for heavier trailer loads. However, because of the increased loading, substantially higher braking requirements are imposed on the trailer brakes, and existing braking cooling systems are ill-equipped for such demands. Secondly, the use of trailers that rely on connection to a gooseneck hitch as disclosed in the '586 Smith patent creates problems when relying on the power unit of the vehicle hauling the trailer for trailer brake cooling. The connection between the hauling vehicle and cooling system must be made every time the trailer is hooked to the hitch, and larger hoses, couplings, etc. are required due to the increased braking requirements of the trailer.
Therefore, a need exists to develop better brake cooling systems, particularly in instances where the power unit of the vehicle must be used for brake cooling. While one solution would be to install a separate engine on the trailer itself for brake cooling, but such an engine requires fuel, oil, and maintenance. In addition, failure of the engine could compromise the braking ability of the trailer axles, and create a potentially dangerous situation if trailer braking is lost.
One brake cooling system is disclosed in U.S. Pat. No. 6,296,087 to Bissonnette et al. While this system uses the rotation of the axle to move the cooling fluid, this system lacks the cooling capacity needed for heavy duty applications. Moreover, the system requires the axle assembly to be modified to include the cooling fluid pumping mechanism, thus complicating the axle assembly manufacture.
The present invention overcomes these drawbacks by the creation of a system that relies on the axle rotation for braking cooling, eliminates the need for an additional engine, permits the use of conventional axle/transmission assemblies, and satisfies the need to obtain increased cooling capacity for large trailers.